Whether you deal with hydraulic or pneumatic seals such as wiper seals, or other types of seals and O-rings on gearboxes and other mechanical equipment, seals must be able to withstand a range of environments and duties, including extreme temperatures, high pressures, chemicals and contamination. With effective maintenance, you can prevent seal failure and achieve better uptime and performance. Here are a few best practices and other tips for getting the optimal performance from your seals. We’ve put together these tips with insights from FPE Seals.

The Importance of Seal Maintenance

For pumps, gearboxes, motors and other sealed equipment, improper maintenance can be expensive. First, a seal failure can cause production stoppage and unplanned downtime. Second, machines may be damaged when a seal fails, leading to additional downtime and repair or replacement costs.

It’s important to learn how to observe the symptoms of seal failure, including leaking, from a small drip to a spray. Seal maintenance should be part of the routine maintenance schedule for equipment, but care should be taken to ensure that seals are stored properly to ensure that they’re ready for deployment when the equipment is needed again.

Maintain Your Seals During Periods of Non-use

Wiper seals, made of flexible elastomer, are available with different profiles. (Image courtesy of FPE Seals.)

Seal maintenance is essential for the best performance of manufacturing equipment—not only during operation but also during periods of nonuse. During storage, degradation and damage to seals may not be as visible as a drip on a running machine, but it is an ideal time to check seals for damage and wear, since maintenance on equipment in storage won’t require downtime. It is vital to check your seals constantly regardless of whether the machinery is being used or not. Seal failures can lead to equipment failures and additional damage.

Proper Storage

According to FPE Seals, the first priority for seal maintenance during periods of nonuse is to ensure that they are being stored properly. This includes putting the seals and their hardware in a cool environment, disassembling the seals and sorting each part individually, making sure not to store seal faces together as they could end up losing their flatness.

Lubrication

Like most machinery, proper and sufficient lubrication is essential for protecting seals from degrading and against wear caused by motion. Check that the correct lubricant is applied to your seals and ensure that they are sufficiently lubricated. Greasing seals is important both during operation of equipment as part of routine maintenance, and during storage.

Contamination

Contamination from metallic shavings, powder, dirt, mud, grit, and other solid particles may occur during operation, but just because your seals are not in use or in motion does not mean that these contaminants are not still present in your seal. Ensure that seals are clean before they enter storage or periods of nonuse.

High Temperatures

Seals, especially elastomer seals, must be stored at the correct temperature. Storage in a hot environment can cause elastomer seals to harden and degrade quickly. Likewise, storage in an environment that is too cold may cause the seal to become brittle. Particles from degrading or breaking seals can go on to contaminate the entire machine or system.

Pressure

According to FPE Seals, it’s important to check for pressure strikes in seals. Seals are rated for specific pressures, and overpressurizing seals can cause damage. If you can see any pressure strikes, then you may need to replace the seal with one that is rated for higher pressure. Certain equipment requires depressurizing before storage. Be sure to read and follow the equipment manual.

Chemical Deterioration

Corrosive fluids can cause a breakdown in seal materials. You can check the seal’s data sheet to ensure that you’re using the right chemicals for your seals. Chemical deterioration can cause a seal to swell or shrink. This is especially relevant for hydraulic systems.

Maintaining Seals During Installation and Use

Of course, proper maintenance and use of equipment seals during use is important as well. Here are some important considerations for prolonged seal life:

Alignment: During installation, mating faces must be properly aligned.
Lubricant: Using an improper lubricant with the seal type or seal material can cause failure.
Vibration: Excessive vibration can affect seal life.
Deflection: Shaft deflection can cause strain on seals.
Temperature and pressure: Operating equipment outside the recommended temperature and pressure can reduce seal life or lead to failure.

Can Split Seals Work for You?

(Image courtesy of AW Chesterton.)

For some large rotating equipment such as utility water pumps, chemical processing dryers or mixers, split seals are installed in place of standard mechanical seals. Split seals are used to seal the rotating shaft of the equipment against its housing.

The main benefit of split seals is that they eliminate the need to disassemble the piece of equipment for installation of the split seal, without removing parts such as a pump, coupler or motor. Positive ROI of split seals typically starts at 65 mm or 2.5 in shaft sizes for single-stage centrifugal pumps.

Split seals are not recommended for hazardous liquids, as they may leak a small amount following installation, before the seal “sets.”

Find out more information about split seals in this e-book from AW Chesterton.

Gearbox Sealing

The parts of a rotary shaft spring. (Image courtesy of Peter R.N. Childs, Mechanical Design Engineering Handbook (Second Edition), 2019.)

For many gearboxes, such as those in motors and drives, lip seals or rotary shaft seals are an essential component. For gearboxes, seals serve two important functions: 1) they retain the lubricant, and 2) they prevent contaminants such as dust and water from entering the equipment.

To maintain lip seals during operation, they should be kept as clean, cool and dry as possible. Painting over a seal or allowing dust or dirt to build up can cause the seal to overheat and fail. As temperatures rise, many lubricant films become thinner, causing the seal to run dry and possibly crack. Nitrile seals and O-rings must also be stored at the correct temperature to prevent degradation.

Solid contaminants such as grit or dirt in the seal can cause leakage or failure by abrading the shaft against the seal, creating a groove where the lubricant can leak.

One common problem with lip seals is that it’s often difficult to clean and repack the grease that is used as a barrier to dust ingress. Grease is used because it traps the dust, but once the grease becomes dirty, many seal designs do not allow that dirty grease to be effectively replaced. This may be something to consider when selecting seals for especially dirty operating environments.

Garter Springs

Garter springs are an important component of a lip seal. The purpose of the garter spring is to maintain a uniform radial force around the shaft, ensuring proper and even contact of the seal against the shaft. Because of this, garter springs are very important for shafts with runout.

By properly installing, lubricating, operating and maintaining all types of seals during use and storage, you can get the best results for the life and productivity of your equipment.